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Which Animals are Ready for AI?
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Maximum fertility to artificial insemination occurs when cows are bred near the end of "standing heat." Ovulation occurs about 12 hours after the end of standing heat. The 12-hour lead time allows the sperm cells to go through a process known as capacitation by the time the egg is released. Fertility decreases slightly when cows are bred a few hours on either side of this target and decreased markedly when breeding occurs more than 12 hours away from the end of "standing heat."
A guide that has proved to work well for timing AI is called the AM/PM rule. At the end of the morning heat detection period, animals detected the prior evening are bred; at the end of the evening heat detection period, those observed that morning are bred. In some situations, AI must be employed once a day wherein all animals detected in the prior 24 hours are bred. Some studies show a little decrease in fertility when this approach is used.
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Table - Using the AM/PM Rule |
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Cows First Showing Oestrus |
Should be Bred |
Too late for Good Results |
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In the morning |
That evening |
Next day |
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In the evening |
The next morning |
After 3:00 p.m. the next day |
Click here to view a video that explains A.I. tips.